The invention relates to a spray booth of the type wherein air flows through the booth and water washes remove particulate matter from the air.
Booths of the type to which the present invention relates are frequently used in spray painting operations wherein an article to be painted is transported through the booth on a conveyor and is spray painted either by hand-held spray nozzles aimed and operated by workers within the booth or by automatic spraying equipment. It is desirable that such booths be suitable for spraying of articles of different shapes and sizes, and suitable for spraying from various directions and locations within the booth.
To provide an even coating on an article being sprayed, it is desirable that only paint particles striking the article directly from a nozzle adhere thereto. It is undesirable that particles deflected from the article be permitted to settle on the article. To these ends, and to supply clean air for workers to breathe, air flows downwardly through the booth at a predetermined rate. The air flow removes particulate material from the booth to prevent undesirable adherence thereof to the workers, to the articles being sprayed, or to other objects within the booth. Certain minimum air flow rates may be needed to supply clean air for workers to breathe for compliance with occupational safety and health standards.
One problem associated with operation of spray booths is that air which is received beneath the floor of the booth after having passed downward through the booth interior typically is laden with a relatively high concentration of particulate matter which must be separated from the air. Discharge of particle-laden air is generally undesirable for environmental reasons, and emission standards presently applicable to many industrial operations specify maximum concentrations of particulate matter for spray booth emissions. In the past, various air-cleaning systems have been proposed to reduce the particle content of spray booth emissions, but such systems have generally been incapable of meeting the above-referenced standards. There is a continuing need for improved means for reducing the concentrations of particulate matter in spray booth emissions.
Another problem associated with operation of some paint spray booths is adherence of particulate matter to the interiors of the side walls of the booths. It is desirable to maintain the interiors of the walls reasonably clean. Also, in booths where windows are provided in the side walls to enable illumination of the interior of the booth from outside the booth, it is desirable to prevent particles from adhering to the interiors of the windows. Thus there is a need for means to prevent build-up of particulate matter on the interior surfaces of booth side walls.
Other considerations which influence the design of spray booths include economy of operation and noise level, which are somewhat interrelated. In industrial spray painting of automobile bodies and the like, it is generally desirable that the power required for pulling air downwardly through a spray booth and through air cleaning apparatus beneath the booth not exceed a predetermined value. Also, it is generally desirable that the noise level inside the booth and around the booth be relatively low. The noise level is partially dependent on the power of the equipment used for moving air through the booth, and dependent on other considerations as well, including air velocity and the configuration of the air cleaning equipment beneath the booth.
Accordingly, it is a general object of the invention to provide a spray booth which is suitable for use in industrial operation and which includes improved apparatus for removing particulate matter from air beneath the booth. It is an additional object of the invention to provide a spray booth having improved means for preventing or reducing adherence of particles to interior wall surfaces of the booth. Additional objects and advantages of the invention are set forth below.